Officials have found no evidence that bird flu is spreading among people in Missouri

NEW YORK — Health officials said Thursday there is no evidence that bird flu is spreading between people after investigating a mysterious infection in Missouri.

The illness reported last month was different from the 30 other bird flu infections in humans in the US so far this year. These cases were in farm workers who had contact with infected dairy cows or chickens.

There was no known contact with an infected animal in the Missouri case, but health officials said Thursday that was the only remaining explanation.

“There is no evidence of person-to-person transmission,” said Dr. Demetre Daskalakis of the Centers for Disease Control and Prevention.

Avian influenza H5N1 it spread widely in the US among wild birds, poultry, cows and a number of other animals. Its growing presence increases the chances that people will be exposed and potentially catch it, officials say.

The most recent of the 31 confirmed human cases are two workers at a commercial egg farm in Franklin County, in southeastern Washington state. The rest: 15 in California, 10 in Colorado, two in Michigan, one in Texas and the odd one in Missouri. Symptoms were mostly mild, including red eyes.

Few details about the Missouri case have been released. The person had pre-existing health problems and was admitted in late August. The patient had a flu test that was positive for influenza A, a broad category of virus. Subsequent tests found partial genetic sequences similar to avian influenza viruses from US dairy cows.

Because the person in Missouri did not work on a farm and had no known contact with an infected animal, health officials looked into the possibility that it came from another person with an undetected infection. This kind of spread would be a worrying sign that the virus could become a more common threat to humans.

They ran complicated blood tests on the patient, five hospital workers and a person described as a “household contact” of the patient – looking for antibodies that would serve as evidence of a previous infection. The household contact had a stomach illness at the same time as the patient but was not initially tested.

On Thursday, CDC officials said the test results were negative for health care workers. The patient and household contact showed signs of previous infection in one round of testing but not in others. Neither met the blood test threshold set by the World Health Organization for a case of bird flu. Domestic contact is not part of the US balance sheet.

Because both became ill at the same time, officials believe the patient and the contact were exposed together to an unknown animal or animal product — ruling out the spread of the virus from one to the other, Daskalakis said.

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